University of Oulu

Mechanism of the Oxidation of Heptafulvenes to Tropones Studied by Online Mass Spectrometry and Density Functional Theory Calculations Sofia M. E. Nilsson, Henning Henschel, Gianmario Scotti, Markus Haapala, Alexandros Kiriazis, Gustav Boije af Gennäs, Tapio Kotiaho, and Jari Yli-Kauhaluoma The Journal of Organic Chemistry 2019 84 (21), 13975-13982 DOI: 10.1021/acs.joc.9b02078

Mechanism of the oxidation of heptafulvenes to tropones studied by online mass spectrometry and density functional theory calculations

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Author: Nilsson, Sofia M. E.1; Henschel, Henning2,3; Scotti, Gianmario1;
Organizations: 1Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, P.O. Box 56 (Viikinkaari 5 E), FI-00014 University of Helsinki, Helsinki, Finland
2Research Unit of Medical Imaging, Physics and Technology, University of Oulu, P.O. Box 5000 (Aapistie 5 A), FI-90220 Oulu, Finland
3Medical Research Center, University of Oulu and Oulu University Hospital, P.O. Box 5000 (Aapistie 5 A), FI-90220 Oulu, Finland
4Department of Chemistry, Faculty of Science, P.O. Box 55 (A.I. Virtasen Aukio 1), FI-00014 University of Helsinki, Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2021111755787
Language: English
Published: American Chemical Society, 2019
Publish Date: 2021-11-17
Description:

Abstract

We have identified the most likely reaction mechanism for oxidizing heptafulvenes to the corresponding tropones by experimental and theoretical investigations. The experimental studies were done by coupling a three-dimensional printed miniaturized reactor with an integrated electrospray ionization needle to a mass spectrometer. Using the experimentally observed ions as a basis, nine alternative reaction pathways were investigated with density functional theory calculations. The lowest energy reaction pathway starts with the formation of an epoxide that is opened upon the addition of a second equivalent of the oxidizing species meta-chloroperoxybenzoic acid. The adduct formed then undergoes a Criegee-like rearrangement to yield a positively charged hemiketal, which on deprotonation dissociates into acetone and tropone. Overall, the reaction mechanism resembles a Hock-like rearrangement.

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Series: Journal of organic chemistry
ISSN: 0022-3263
ISSN-E: 1520-6904
ISSN-L: 0022-3263
Volume: 84
Issue: 21
Pages: 13975 - 13982
DOI: 10.1021/acs.joc.9b02078
OADOI: https://oadoi.org/10.1021/acs.joc.9b02078
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
Subjects:
Funding: Computational resources were granted by the CSC-IT Center for Science in Espoo, Finland. Nina Sipari is acknowledged for the LC−MS measurements. Financial support was provided by the Academy of Finland (projects 276627, 257316, and 307464) and the Doctoral Program in Drug Research, University of Helsinki.
Copyright information: © 2019 American Chemical Society. This is an open access article published under Creative Commons (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the author and source are cited.
  https://creativecommons.org/licenses/by/4.0/